You get an inverter 12V-115V, and plug the NUC into it. I see a 12v NUC in roadmap, but Intel has not published any specs. I am putting mine in a Jeep using a cheap invertor, and have run my laptop off the same inverter.
Hope this speeds up your carputer!
Keep us posted on monitor and other details!
Can you send me the make/model of the inverter you are using in your Jeep? I'd like to add it to our customer-reported compatibility list.